I have a different idea concerning Zod's symbol. Ratherthan it being a specific letter of something like that, what if it's a stylistic design used by the Zod "clan" of Krypton? In terms of the pentagon itself, I could imagine it being similar in function to an Egyptian cartouche. Since shapes are limited, it makes sense that the noble houses would have used simple designs to identify their houses, with or without any direct meaning or interpretation.